1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a side-edge backlight module.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that liquid crystal molecules are interposed between two parallel glass substrates and a plurality of vertical and horizontal fine electrical wires is arranged between the two glass substrates, whereby the liquid crystal molecules are controlled to change direction by application of electricity in order to refract light emitting from the backlight module for generating images. Since the liquid crystal display panel itself does not emit light, light must be provided by the backlight module in order to normally display images. Thus, the backlight module is one of the key components of an LCD. The backlight module can be classified as two types, namely side-edge backlight module and direct backlight module, according to the position where light gets incident. The direct backlight module arranges a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED) at the back side of the liquid crystal display panel to form a planar light source that directly provides lighting to the liquid crystal display panel. The side-edge backlight module arranges a light source of LED light bar at an edge of a back panel to be located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate through a light incident face of the light guide plate and is projected out through a light exit face of the light guide plate after being reflected and diffused to thereby form a planar light source for the liquid crystal display panel.
Referring to FIG. 1, a side-edge backlight module generally comprises a backplane 100, a reflector plate 200 arranged inside the backplane 100, a light guide plate 300 disposed on the reflector plate 200, a backlight source 400 arranged inside the backplane 100, a heat dissipation plate 500 arranged between the backlight source 400 and the backplane 100, and a support 600 arranged inside the backplane 100 to support the light guide plate 300. The backplane 100 comprises a bottom board 102 and a side board 104 connected to the bottom board 102. The backlight source 400 is mounted on the heat dissipation plate 500. The heat dissipation plate 500 is fixed to the bottom board 102 of the backplane 100 by screws. Heat emitting from the backlight source 400 is transferred through the heat dissipation plate 500 to the bottom board 102 of the backplane 100 and is then subjected to heat exchange with the surrounding atmosphere through the backplane 100. To facilitate heat dissipation, the backplane 100 is often made of SECC (Steel, Electrogalvanized, Cold-Rolled, Common) steel in combination with aluminum material, or solely made of aluminum alloy, and consequently, a relatively large amount of metal is used.
However, using a large amount of metal to make the backplane makes the backlight module relatively heavy. In addition, the backplanes are generally made of one or two kinds of material, so that the cost of backplane is susceptible to variation of raw material expense, making it hard to control cost.